Evaluating the impacts of mesoscale eddies on abundance and distribution of neon flying squid in the Northwest Pacific Ocean

Abstract

Mesoscale eddies are ubiquitous in global oceans yielding significant impacts on marine life. As a short-lived pelagic squid species, the population of neon flying squid (Ommastrephes bartramii) is extremely sensitive to changes in ambient oceanic variables. However, a comprehensive understanding of how mesoscale eddies affect the O. bartramii population in the Northwest Pacific Ocean is still lacking. In this study, a 10-year squid fisheries dataset with eddy tracking and high-resolution reanalysis ocean reanalysis data was used to evaluate the impact of mesoscale eddies and their induced changes in environmental conditions on the abundance and habitat distribution of O. bartramii in the Northwest Pacific Ocean. A weighted-based habitat suitability index (HSI) model was developed with three crucial environmental factors: sea surface temperature (SST), seawater temperature at 50-m depth (T50m), and chlorophyll-a concentration (Chl-a). During years with an unstable Kuroshio Extension (KE) state, the abundance of O. bartramii was significantly higher in anticyclonic eddies (AEs) than that in cyclonic eddies (CEs). This difference was well explained by the distribution pattern of suitable habitats in eddies derived from the HSI model. Enlarged ranges of the preferred SST, T50m, and Chl-a for O. bartramii within AEs were the main causes of more squids occurring inside the warm-core eddies, whereas highly productive CEs matching with unfavorable thermal conditions tended to form unsuitable habitats for O. bartramii. Our findings suggest that with an unstable KE background, suitable thermal conditions combined with favorable foraging conditions within AEs were the main drivers that yielded the high abundance of O. bartramii in the warm eddies.

Fishing through the cracks: The unregulated nature of global squid fisheries

“…In addition, since there are currently no data sharing agreements between the countries fishing squid, there is also no regional estimation of squid abundance in any of the four regions in this study, and any estimates of stock status or comprehensive catch per unit effort (CPUE) are not possible (58)(59)(60). While squid fisheries are notoriously difficult to evaluate (61)(62)(63)(64)(65)(66)(67)(68)(69), concerns for stock sustainability are echoed in scientific literature, management statements, and journalism pertaining to the relevant stocks. For example, evidence suggests concerns over the declining abundance of squid stocks both globally (6) and within multiple regions: the NW Pacific Ocean (52,70,71), SW Atlantic Ocean (2, 37, 60), SE (21,42).…”

Bioluminescent eddies of the World Ocean

“…It is believed that the preferred ranges of temperature and phytoplankton (traced by chlorophyll‐ a ) were the main causes of more squid occurring inside the warm‐core eddies. [ 32 ] Presumably, the bioluminescence as well as a high abundance of squid and mesopelagic fish act as a lure attracting apex predators. In this respect, high catch rates of tuna were observed at the periphery of anticyclonic eddies.…”

Mixing Dynamics Within the Kuroshio Area Are Reflected in Dissolved Inorganic Radiocarbon Values

“…This enhancement is particularly prominent in areas where cold‐core cyclonic eddies are observed, that is, the area close to where station B2 is located (Figure 7). Since cyclonic eddies developed between the Kuroshio and the coast are responsible for upwelling‐induced eutrophication (Uchiyama et al., 2017; Zhang et al., 2022), higher surface Chl a concentrations (1.94 ± 0.35 μg $$\cdot $$ L −1 ) were observed at station B2 than those at stations P5 (1.49 ± 0.58 μg $$\cdot $$ L −1 ) and YB‐1 (1.13 ± 0.59 μg $$\cdot $$ L −1 ) in the upper 50 m (Figure 4d and Table S2 in Supporting Information ).…”